Methods of forming button type batteries and to button type battery insulating and sealing gaskets

ABSTRACT

A method of forming a button-type battery includes: a) positioning first and second terminal housing members in facing juxtaposition to one another, and providing an anode, a cathode and an electrolyte intermediate the first and second terminal housing member central portions; b) providing a peripheral insulative sealing gasket intermediate the first and second terminal housing members, the insulative sealing gasket being in the shape of an annulus and having a radial extent which extends radially outward beyond the surrounding peripheral portions of the first and second terminal housing members; c) moving at least one of the juxtaposed first and second terminal housing members in the direction of the other to push the first terminal housing member container wall against the first gasket face and to simultaneously force the second terminal housing member peripheral portion against the second gasket face, and continuing such moving to bend the insulative gasket about the container wall and force it to be received within the first terminal housing member; and d) after the moving step, crimping the container wall and sealing gasket against the peripheral portion of the second terminal housing member to form an enclosed housing. An alternate method includes: i) providing a discrete, pre-formed peripheral insulative sealing gasket in the shape of an annulus; and ii) positioning the discrete, pre-formed sealing gasket within the first terminal housing member, then crimping to seal. A novel gasket construction is also disclosed.

RELATED PATENT DATA

This patent resulted from a divisional application under 37 CFR §1.60(b)of prior application Ser. No. 08/649,925 filed on May 16, 1996, entitled"Method Of Forming Thin Profile Batteries And A Thin Profile BatteryInsulating And Sealing Gasket", by the following named inventor: Mark E.Tuttle , now U.S. Pat. No. 5,662,718; which is a file wrappercontinuation application of prior application Ser. No. 08/348,543 filedon Dec. 1, 1994, entitled "Method Of Forming Button-Type Batteries And AButton-Type Battery Insulating And Sealing Gasket", by the followingnamed inventor: Mark E. Tuttle , now abandoned.

BACKGROUND OF THE INVENTION

Button-type batteries are small, thin energy cells that are commonlyused in watches and other electronic devices requiring a thin profile. Aconventional button-type battery includes two electrodes in the form ofan anode and a cathode. These are typically separated by a porousseparator. An electrolyte is present within pores of the separator.

These internal battery components are housed within a metal casing orhousing formed by a lower conductive can and an upper conductive lid. Acommon prior art material for the can and lid is stainless steel. Thecan is typically in electrical contact with the cathode to form thepositive battery terminal, and the lid is in electrical contact with theanode to form the negative battery terminal. The can and lid are crimpedor pressed together to form a fluid-tight seal which entirely enclosesthe anode, cathode, separator, and electrolyte. An electricallyinsulating sealing gasket is provided within the primary seal betweenthe lid and can to electrically isolate the two housing members.

This invention principally concerns the provision of the sealing gasketmaterial within the crimp.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is an exploded fragmentary cross-sectional view of button-typebattery components illustrative of a method of forming a button-typebattery in accordance with an aspect of the invention.

FIG. 2 is a top view of a gasket component of FIG. 1.

FIG. 3 is a fragmentary sectional view of button-type battery componentsin position in a method of forming a button-type battery in accordancewith the invention.

FIG. 4 is a fragmentary sectional view of button-type battery componentsin position in an alternate method of forming a button-type battery inaccordance with the invention.

FIG. 5 is a fragmentary sectional view of button-type battery componentsin process during a method of forming a button-type battery inaccordance with the invention.

FIG. 6 is a view of the FIG. 5 battery components at a point in timesubsequent to the processing step illustrated by FIG. 5.

FIG. 7 is a view of the FIG. 5 battery components at a point in timesubsequent to the processing step illustrated by FIG. 6.

FIG. 8 is a sectional view of a button-type battery produced inaccordance with a method of the invention, and differs from the FIG. 7construction in utilization of an alternate sized sealing gasket.

FIG. 9 is a fragmentary side sectional view of a discrete, pre-formedperipheral insulating sealing gasket utilized in an alternate method offorming a button-type battery in accordance with another aspect of theinvention.

FIG. 10 is reduced scale top view of the FIG. 9 sealing gasket.

FIG. 11 is a fragmentary exploded view of button-type batterycomponents, including the gasket of FIGS. 9 and 10, positioned forassembly in accordance with an aspect of the invention.

FIG. 12 is a side sectional view of the components of FIG. 11 shown inprocess during a method of forming a button-type battery in accordancewith an aspect of the invention.

FIG. 13 is a fragmentary sectional view of button-type batterycomponents of FIG. 11 shown in a finished assembled state.

FIG. 14 is a side sectional view of a button-type battery insulativesealing gasket in accordance with the invention.

FIG. 15 is an enlarged view of a portion of the button-type batteryinsulative sealing gasket of FIG. 14.

FIG. 16 is a view of the FIG. 14 gasket at the FIG. 15 scale, andillustrates the gasket in a sealed or crimped relationship with respectto first and second button-type battery terminal housing members.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws "to promote the progressof science and useful arts" (Article 1, Section 8).

In accordance with a first aspect of the invention, a method of forminga button-type battery comprises the following steps:

providing a conductive first terminal housing member having asurrounding peripheral portion and a central portion intermediate thesurrounding peripheral portion, the surrounding peripheral portioncomprising a transversely projecting peripheral container wall;

providing a conductive second terminal housing member having asurrounding peripheral portion and a central portion intermediate itssurrounding peripheral portion;

positioning the second terminal housing member and the first terminalhousing member in facing juxtaposition to one another, and providing ananode, a cathode and an electrolyte intermediate the first and secondterminal housing member central portions;

providing a peripheral insulative sealing gasket intermediate the firstand second terminal housing members, the insulative sealing gasket beingin the shape of an annulus and having a radial extent which extendsradially outward beyond the surrounding peripheral portions of the firstand second terminal housing members, the insulative sealing gaskethaving opposing first and second faces, the first face facing the firstterminal housing member, the second face facing the second terminalhousing member;

moving at least one of the juxtaposed first and second terminal housingmembers in the direction of the other to push the first terminal housingmember container wall against the first gasket face and tosimultaneously force the second terminal housing member peripheralportion against the second gasket face, and continuing such moving tobend the insulative gasket about the container wall and force it to bereceived within the first terminal housing member; and

after the moving step, crimping the container wall and sealing gasketagainst the peripheral portion of the second terminal housing member toform an enclosed housing which retains and protects the anode, cathodeand electrolyte; the insulative gasket insulatingly sealing between thecrimped container wall and the second terminal housing member peripheralportion.

In accordance with another aspect of the invention, a method of forminga button-type battery comprises the following steps:

providing a conductive first terminal housing member having asurrounding peripheral portion and a central portion intermediate thesurrounding peripheral portion, the surrounding peripheral portioncomprising a transversely projecting peripheral container wall;

providing a conductive second terminal housing member having asurrounding peripheral portion and a central portion intermediate itssurrounding peripheral portion;

providing a discrete, pre-formed peripheral insulative sealing gasket,the gasket being in the shape of an annulus and comprising at least inpart a substantially annular "L" cross sectional shape defining anannular "L" base portion and an annular "L" stem portion;

positioning the discrete, pre-formed sealing gasket within the firstterminal housing member with the "L" stem portion extending internallyalong the container peripheral wall;

positioning the second terminal housing member and the first terminalhousing member in facing juxtaposition to one another, and providing ananode, a cathode and an electrolyte intermediate the first and secondterminal housing member central portions, the second terminal housingmember peripheral portion being received against the "L" base portion ofthe positioned sealing gasket; and

crimping the container wall and sealing gasket against the peripheralportion of the second terminal housing member to form an enclosedhousing which retains and protects the anode, cathode and electrolyte;the insulative gasket insulatingly sealing between the crimped containerwall and the second terminal housing member peripheral portion.

In accordance with still a further aspect of the invention, abutton-type battery insulative sealing gasket comprises:

an annular body at least a portion of which has a substantially "L"cross sectional shape;

the "L" cross sectional shape defining an annular "L" base portion, the"L" base portion being configured to receive an inner sealing portion ofa peripheral portion of a button-type battery terminal lid, the "L" baseportion having a radial length and an inner radial portion and an outerradial portion;

the "L" cross sectional shape defining an annular "L" stem portion, the"L" stem portion being configured to receive an outer sealing portion ofa peripheral portion of a button-type battery terminal lid, the "L" stemportion having a transverse length and an inner transverse portion andan outer transverse portion; and

the "L" base portion having a thickness which varies along its radiallength, the base thickness being greater at the inner radial portionthan at the outer radial portion.

More particularly and first with reference to FIGS. 1 and 2, button-typebattery components for assembly are indicated generally with referencenumeral 10. Such are comprised of a first terminal housing member 12having a surrounding peripheral portion 14 and a central portion 16intermediate surrounding peripheral portion 14. Portion 14 is in theform of a substantially normal peripheral container wall which projectstransversely relative to central portion 16. In the illustratedembodiment, container wall 14 projects to a first distance 18 relativeto central portion 16. An example first distance 18 would be 0.033inches.

The button-type battery components also include a second terminalhousing member 20 having a surrounding peripheral portion 22 and acentral portion 24 intermediate peripheral portion 22. Conventionally inthe art, first terminal housing member 12 is commonly referred to as a"container" or "can", while second terminal housing member 20 istypically referred to as a "lid". Second terminal housing member 20 andfirst terminal housing member 12 are positioned in opposing facingjuxtaposition to one another. An anode 26, a cathode 28 and liquidelectrolyte 30 are provided intermediate first and second terminalhousing member central portions 16 and 24, respectively. A porousseparator 32 is also typically provided intermediate cathode 28 andanode 26. Components 26, 28, 30 and 32 could be provided either withinfirst terminal housing member 12 or second terminal housing member 20,with positioning relative to second terminal housing member 20 beingshown and preferred.

A peripheral sealing gasket 34 is provided intermediate first terminalhousing member 12 and second terminal housing member 20. Gasket 34 is inthe shape of an annulus, and has a radial extent 36 which extendsradially outward beyond surrounding peripheral portions 14 and 22, asshown. Radial extent 36 defines a second distance which is less thanfirst distance 18. Gasket 34 has opposing first and second faces 38, 40,respectively, with first face 38 facing first terminal housing member 12and second face 40 facing second terminal housing member 20. Gasket 34is of constant thickness (FIG. 1) and has a constant outer radius (FIG.2).

Preferred techniques for providing and positioning the gasketintermediate the housing members are described with reference to FIGS. 3and 4. In one embodiment 10a shown in FIG. 3, gasket second face 40 isadhered against second terminal housing member peripheral portion 22prior to the step of positioning the first and second terminal housingmembers in juxtaposition to one another. An example and preferredadhesive is a tacky asphalt, such as Pioneer 760™ made by PioneerAsphalt Company of Lawrenceville, Ill. In an alternate embodiment 10b asshown in FIG. 4, gasket first face 38 is placed against container wall14 prior to the step of positioning the first and second terminalmembers in juxtaposition to one another. Again, preferably an adhesivesuch as the above Pioneer 760™ is used intermediate gasket first face 38and container wall 14 for temporarily retaining gasket 34 in theillustrated position. The adhesive should not, however, be so strong asto prevent subsequent breaking and sliding of gasket 34 relative towalls 14, as will be apparent from the continuing discussion.Preferably, the anode, the cathode, the electrolyte, and the separatorare positioned relative to one of the first or second housing membersbefore the step of providing gasket 34 in its intermediate position.

Referring to FIGS. 5-7, at least one of juxtaposed first terminalhousing member 12 or second terminal housing member 20 is moved in thedirection of the other to push first terminal housing member peripheralwall 14 against first gasket face 38 and to simultaneously force secondterminal housing member peripheral portion 22 against second gasket face40. This will cause sliding movement of first gasket face 38 relative tothe outer edge of container wall 14, as well as bending of gasket 34(FIG. 5). Such movement is continued to bend insulative gasket 34 aboutcontainer wall 14 and force gasket 34 to be received within firstterminal housing member 12 (FIG. 6). After such bending and placement ofgasket 34 within first container 12, container wall 14 and adjoiningsealing gasket material 34 are crimped against peripheral portion 22 ofsecond terminal housing member 20 (FIG. 7) to form an enclosed housingwhich retains and protects the anode, cathode and electrolyte.Insulative gasket 34 insulatingly seals between crimped container wall14 and second terminal housing member peripheral portion 22. FIG. 7illustrates a finished construction designated with numeral 45.

Referring to FIGS. 1 and 7, second distance 36 is preferably gauged tobe less than first distance 18 such that upon finished folding andcrimping, the outer terminus of gasket 34 aligns with the outer terminusof crimped container wall 14. Due to container wall 14 being bent aboutan effective larger radius than gasket 34, second distance 36 will beless than first distance 18 to accomplish such objective.

FIG. 8 illustrates an alternate embodiment 45a whereby second distance36 is greater than or equal to first distance 18. As shown, gasket 34ahas an outer terminus which projects outwardly beyond the terminus ofcontainer wall 14 after crimping. Such would provide an advantage ofpositioning insulative material between can 12 and lid 20 in thisregion. In either embodiment if desired, gasket 34 can be constructed toextend radially inward to contact the outer radial edge of cathode 28,thereby providing an alignment function within the housing relative forcathode 28.

A method of forming a button-type battery as described above enables thegasket to be made from extremely thin sheet stock, and minimizes finalbattery thickness. Preferred thickness is from 2 to 4 mils.Polypropylene is a preferred material which can be formed by coldpressing or hot pressing. Current button-type battery gaskets inindustry are formed by injection molding, and are difficult to producein desired shapes at thicknesses less than 7 mils.

An alternate embodiment and method of construction are described withreference to FIGS. 9-13. For simplification and ease of discussion, noanode, cathode, or electrolyte are shown with respect to theconstruction. Like numerals from the first-described embodiments areutilized where appropriate, with differences of construction beingindicated with different numerals. An insulative sealing gasket 50 isprovided as a discrete, pre-formed mass in the shape of an annulus. Suchcomprises at least in part a substantially annular "L" cross-sectionalshape, defining an annular "L" base portion 52 and an annular "L" stemportion 54.

Referring to FIG. 12, discrete pre-formed sealing gasket 50 ispositioned within first terminal housing member 12 with "L" stem portion54 extending internally along container peripheral wall 14. Preferably,gasket base 52 is adhered by a tacky adhesive to first terminal housingmember 12, with the Pioneer 760™ being an example. Second terminalhousing member 20 is moved into facing juxtaposition against "L" baseportion 52 of sealing gasket 50.

Referring to FIG. 13, container wall 14 and gasket stem 54 are crimpedagainst peripheral portion 22 of second terminal housing member 20 toform an enclosing housing which retains and protects the anode, cathodeand the electrolyte (not shown). The finished construction is indicatedwith numeral 51. A preferred material of construction is polypropylenehaving from 1% to 3% ethylene.

In accordance with another aspect of the invention, a preferredembodiment button-type battery insulative sealing gasket is indicatedgenerally with reference numeral 56 in FIGS. 14-16. Such is comprised ofan annular body 58 having a substantially "L" cross-sectional shape. The"L" cross-sectional shape defines an annula "L" base portion 60 and anannular "L" stem portion 70. Base portion 60 is configured to receive aninner sealing portion of a peripheral portion 22 of a button-typebattery terminal lid 20 for which the gasket is principally adapted. "L"base portion 60 has a radial length 62 (FIG. 15) and, for purposes ofdiscussion, has an inner radial portion 64 and an outer radial portion66.

Base portion 60 has a thickness which varies along its radial length 62,being greater at inner radial portion 64 than at outer radial portion66. The illustrated change in the base portion thickness preferablyoccurs along a base arc 68 which is sized and shaped to mate with acorrespondingly shaped arc of peripheral portion 22 of button-type abattery terminal lid 20 for which gasket 56 is adapted.

Stem portion 70 is configured to receive an outer sealing portion orsurface 99 (FIG. 15) of peripheral portion 22 of button-type batteryterminal lid 20. Stem portion 70 has a transverse length 72 which, forpurposes of the continuing discussion, defines an inner transverseportion 76 and an outer transverse portion 78. "L" stem portion 70 alsohas a thickness which varies along its transverse length 72, with thestem thickness being greater at inner transverse portion 76 than atouter transverse portion 78. The thickness change for stem portion 70occurs at a substantially perpendicular step 80, as opposed to along anarc as occurs in the base portion. Stem portion 70 angles from baseportion 60 at slightly greater than 90°. This makes it easier to insertgasket 56 into the can and prevent stem portion 70 from folding inwardand interfering with lid insertion.

Referring to FIG. 16, the components are positioned and crimped as shownto produce a peripheral seal for a button-type battery. Such a gasketconstruction provides two advantages. First, the greater mass ofmaterial defined at the gasket fold by step 80 substantially completelyfills any outer void between lid 20 and can 12. Second, the enlargedinner radial portion of base 60 defined by arc 68 can be utilized toengage the outer radial edge of the cathode (not shown) to provide analignment function with the battery to such cathode.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

I claim:
 1. A button-type battery insulative sealing gasket, theinsulative sealing gasket before being crimped in a batterycomprising:an annular body at least a portion of which has asubstantially "L" cross sectional shape; the "L" cross sectional shapedefining an annular "L" base portion, the "L" base portion beingconfigured to receive an inner sealing portion of a peripheral portionof a button-type battery terminal lid, the "L" base portion having aradial length and an inner radial portion and an outer radial portion;the "L" cross sectional shape defining an annular "L" stem portion, the"L" stem portion being configured to receive an outer sealing portion ofthe peripheral portion of the button-type battery terminal lid, the "L"stem portion having a transverse length and an inner transverse portionand an outer transverse portion, the "L" stem portion having a thicknesswhich varies along its transverse length, the stem thickness beinggreater at the inner transverse portion than at the outer transverseportion, the change in the stem portion thickness occurring at asubstantially perpendicular step; and the "L" base portion having athickness which varies along its radial length, the base thickness beinggreater at the inner radial portion than at the outer radial portion. 2.A button-type battery insulative sealing gasket, the insulative sealinggasket before being crimped in a battery comprising:an annular body atleast a portion of which has a substantially "L" cross sectional shape;the "L" cross sectional shape defining an annular "L" base portion, the"L" base portion being configured to receive an inner sealing portion ofa peripheral portion of a button-type battery terminal lid, the "L" baseportion having a radial length and an inner radial portion and an outerradial portion; the "L" cross sectional shape defining an annular "L"stem portion, the "L" stem portion being configured to receive an outersealing portion of the peripheral portion of the button-type batteryterminal lid, the "L" stem portion having a transverse length and aninner transverse portion and an outer transverse portion, the "L" stemportion having a thickness which varies along its transverse length, thestem thickness being greater at the inner transverse portion than at theouter transverse portion, the change in the stem portion thicknessoccurring at a substantially perpendicular step; and the "L" baseportion having a thickness which varies along its radial length, thebase thickness being greater at the inner radial portion than at theouter radial portion, the change in the base portion thickness occurringalong a base arc, the base arc being sized and shaped to mate with acorrespondingly shaped arc of the peripheral portion of the button-typebattery terminal lid for which the gasket is adapted.
 3. An insulativesealing gasket for a thin profile battery, the thin profile batterybeing defined by a thickness which is less than a maximum lineardimension of its anode, the insulative sealing gasket before beingcrimped in a battery comprising:an annular body at least a portion ofwhich has a substantially "L" cross sectional shape; the "L" crosssectional shape defining an annular "L" base portion, the "L" baseportion being configured to receive an inner sealing portion of aperipheral portion of a button-type battery terminal lid, the "L" baseportion having a radial length and an inner radial portion and an outerradial portion; the "L" cross sectional shape defining an annular "L"stem portion, the "L" stem portion being configured to receive an outersealing portion of the peripheral portion of the button-type batteryterminal lid, the "L" stem portion having a transverse length and aninner transverse portion and an outer transverse portion, the "L" stemportion having a thickness which varies along its transverse length, thestem thickness being greater at the inner transverse portion than at theouter transverse portion; and the "L" base portion having a thicknesswhich varies along its radial length, the base thickness being greaterat the inner radial portion than at the outer radial portion.
 4. A thinprofile battery defined by a thickness which is less than a maximumlinear dimension of its anode, comprising:a conductive first terminalhousing member having a surrounding peripheral portion which comprises atransversely projecting peripheral container wall; a conductive secondterminal housing member having a surrounding peripheral portion; agasket in the shape of an annulus and comprising at least in part asubstantially annular "L" cross sectional shape defining an annular "L"base portion, an annular "L" stem portion, and a step along the stemportion; the step comprising an upper surface which is substantiallyperpendicular to a lateral surface of the stem portion; the stem portioncomprising an above-step section elevationally above the step, the "L"stem portion extending internally along the peripheral container wall,the second terminal housing member peripheral portion being receivedagainst the "L" base portion of the gasket, the first terminal housingmember peripheral container wall and the sealing gasket being againstthe peripheral portion of the second terminal housing member to form anenclosed housing; and the above-step section of the stem portion beingover and against the upper surface of the step.